1. Field of the Invention
The present invention relates to an image forming apparatus, such as an electrophotographic multi-function peripheral (MFP), facsimile, or printer, and in particular, to an electrophotographic apparatus having a user-replaceable unit.
2. Description of the Related Art
In an electrophotographic image forming apparatus, such as a printer, a facsimile, or a MFP having function of a printer and a facsimile, for example, a photosensitive element and a cleaner or a developing unit around the photosensitive drum are unitized as a single unit, and the unit is configured to be freely replaced with respect to the main body of the image forming apparatus (apparatus main body). This unit is consumables and should be replaced when the lifetime has come to an end or the like. In this case, an image carrier unit equipped with a photosensitive drum should have a toner supply unit in order to be supplied with toner as developer.
In an image forming apparatus, the density or the like of an image to be formed is affected by the environmental conditions, such as temperature and humidity, the history conditions, such as a residual toner amount, or the like. Thus, in the image carrier unit, it is necessary that the residual toner amount at the toner supply unit which supplies toner should be detected.
In the related art, an electrophotographic apparatus is known in which ease and simplification of determination on whether a unit (a replaceable unit with respect to an apparatus main body) is new or old are achieved, thereby increasing lifetime management accuracy of the unit (Japanese Unexamined Patent Application Publication No. 6-118736). In this apparatus, an electronic element which is configured to be destroyed through energization from the apparatus main body is arranged in the unit, and the determination on whether the unit is old or new products is made on the basis of the determination on whether the electronic element (new product detection element) is destroyed.
On the other hand, when there is a problem in an image formed by the image forming apparatus, it is necessary to determine whether the problem is caused by the apparatus main body or the unit. For this purpose, there is a case where a user or the like mounts a new unit for a test in the main body of the image forming apparatus in which a problem arises and checks the operation of the unit. In this case, in the apparatus as described in Japanese Unexamined Patent Application Publication No. 6-118736, if a new unit is mounted, this unit is determined as new, and a new product detection element, such as a fuse or the like, is destroyed (fused). Thereafter, an image is output to carry out operation check.
For this reason, in this case, when a problem is caused by the apparatus main body, a unit (new unit) which has not problem is replaced, and the unit which has no problem is wasted. Thus, a configuration in which the new product detection element is fused after a predetermined value (a number of counts of image formation) is reached, not just after a new unit is mounted, is known (Japanese Unexamined Patent Application Publication No. 2006-145765). That is, Japanese Unexamined Patent Application Publication No. 2006-145765 describes a technique in which fusing is not made until a number of sheets on which images are formed reaches a predetermined number of sheets, and a new unit is recognized as new even when the new unit is used in another apparatus after the new unit has been used for a test.
If a new product detection element is fused, a counter which is provided in an apparatus main body is set to “0”, and determination of the lifetime of a unit can be made on the basis of the counter (Japanese Patent No. 3132073).
An image forming apparatus is also known which includes a toner density detection unit detecting a toner density, an operation detection unit detecting a history on whether a toner cartridge is in an initial state in which the toner cartridge has not been operated or in a state in which the toner cartridge has been operated, and a memory storing data on the history detected by the operation detection unit (Japanese Unexamined Patent Application Publication No. 9-185236). In this case, when a new toner cartridge which has not been operated is loaded, the history data is initialized, and an image forming operation is carried out under operation conditions set in advance. That is, in this image forming apparatus, a number image formation and related processing are performed in the image forming operation, in order to achieve stable image quality.
On the other hand, as described above, an image forming apparatus includes a plurality of types of units, and the units are different in expiration date. For this reason, it is preferable that the units are replaceable separately.
However, in a conventional image forming apparatus as described above, an image carrier unit and a toner supply unit are integrated as a single process cartridge, and are not replaceable separately. When the units are replaceable separately, a detection unit should be provided in each unit to detect whether the unit is new or not. For example, when an electronic component, such as a fuse, is used for the detection unit, the fuse should be provided in each unit, and an electric circuit should be provided so as to supply power to the fuse. For this reason, there is a limitation on making the entire apparatus compact.